The present invention relates to a multi-link coal planer which has a pair of intermediate units located between a central unit and loading heads, in which each of the intermediate units basically comprises a base plate and a support with a plurality of planing knives and a bottom knife.
The intermediate units of coal planers of the aforementioned kind have a plurality of planing knives and a bottom knife. The planing knives are connected each with a carrier which in turn is connected to the support of the intermediate unit. In this construction the planing knives are fixedly connected to the intermediate unit. This will result that during movement of the coal planer in a direction opposite to the planing direction, the back faces of the planing knives will slide on the mine face to remove in an undesired manner fine coal or coal dust therefrom. In addition, the planing knives will be heated due to the frictional engagement with the mine face in an undesired manner and sometimes torn from the knife carrier. Furthermore, to overcome the friction between the knives and the mine face, the drive reciprocating the coal planer along the mine face has to be constructed for a higher output than would be necessary when such friction losses could be avoided.
The same disadvantages are inherent with the bottom knife on the intermediate units of known coal planers, since such bottom knives will, during movement of the coal planer in a direction opposite its planing movement, slide on the sole of the mine gallery and on the mine face, whereby again fine coal or coal dust will be created in an undesired manner and the bottom knife will be heated during such sliding movement. At the same time the power of the drive has likewise to be increased.